There are several devices, of which I am aware, which provide audio, as well as visual, signals and alarms in the event of fire. Normally, such devices are fixed in place in those portions of a building where fire or smoke is likely to occur. An example of such a device which provides an audio alarm is described in U.S. Pat. No. 2,626,586 issued to Mendes. While these devices are quite useful for warning individuals of the presence of a fire, they are not useful for aiding individuals, such as firemen, in locating persons who may be trapped in the fire.
I am also aware of the existence of personal alarm devices, wherein visual and audio alarms are combined in a single device for, i.e., warding off attackers. An example of such a device is described in U.S. Pat. No. 2,782,748 issued to Zegarowitz. However, to the best of my knowledge no one has provided a personal alarm device which has both audio and visual stimuli that would aid in the location of victims who may be trapped in a fire.
The audio alarms of Mendes and Zegarowitz, while being suitable for their purpose, are not readily adaptable for use in aiding in the location of trapped individuals. The audio alarms of both Mendes and Zegarowitz are activated by the release of compressed air or gas from a cartridge. Such cartridges are not capable of holding sufficient quantities of air or gas to maintain a prolonged audio signal which sounds for a sufficient period of time to permit location of an individual in a fire. If the cartridges were made larger, then those devices would lose whatever portability they had.
The visual alarm of Zegarowitz, while being suitable for its purpose is also not readily useful for aiding in the location of trapped individuals. The visual alarm of Zegarowitz is a lamp which, during daylight hours, would not be readily visible. Also such a device would do little if the person were trapped on upper floors of a burning building.
Accordingly, it can be seen that there remains a need for a simple, lightweight and portable personal alarm device, which has both audio and visual alarms, both of which are readily detectable, for aiding in the location of individuals who are trapped in fires, or in other emergencies.